1. Field of the Invention
The present invention relates to a heat dissipation device for electronic devices, and particularly to a heat dissipation device incorporating a plurality of stacked fins.
2. Related Art
Electronic devices such as central processing units (CPUs) generate a lot of heat during normal operation. If the heat generated is not properly dissipated, it can deteriorate their operational stability and damage associated electronic devices. Thus the heat must be removed quickly and efficiently to ensure normal operation. A heat dissipation device is often attached to a top surface of a CPU, to remove heat therefrom.
A conventional heat dissipation device is made by extrusion, which significantly limits the height of its formed fins. To resolve the problem, another kind of heat dissipation device has been developed. Fins of such device are folded from a metal sheet. The folded fins are then adhered to a base which is for contacting an electronic device. The device has a large heat dissipating surface area. However, because the fins are adhered to the base air gap inevitablely exists between the base and the fins. This reduces heat transmit efficiency from the base to the fins.
Thus a cylindrical heat dissipation device has been developed. U.S. Pat. No. 6,330,908 shows such kind of conventional heat dissipation device. The heat dissipation device comprises a cylindrical core and a plurallity of vertical fins attachably surrounding the core. A mounting plate is fixed on a top of the core by screws. A fan is fixed on the mounting plate by screws. However, air passages between the fins are vertical which do not consist with spiral air flow of the fan. Furthermore, the mounting plate locates between the fan and the fins and extends transversely the air flow of the fan. These obstructs the air flow of the fan flowing through the fins and limits heat dissipation of the fins, thereby reducing the efficiency of heat transfer of the heat dissipation device.
Then, another kind of cylindrical heat dissipation device having spiral air passages formed therein is developed. However, a mounting plate on which a fan is mounted is stilled fixed on a top of a cylindrical core of the heat dissipation device between the fan and the fins, which obstructs the air flow of the fan flowing through the fins and limits heat dissipation of the fins, thereby reducing the efficiency of heat transfer of the heat dissipation device.